Lime
Member
- Messages
- 2,749
- Location
- East of England
From what I've seen of floods directly, the sewage doesn't have a chance to mix with flood waters.
The majority is pushed back up through the sewage system by the flood waters.
The initial trapped-air voids within the sewers, compressed by flood water above spurting through manhole/access covers, pushes the entire sewer contents back up smaller pipes creating a thick "soup".
Often the sewage pipes are the first way some areas get flooded because they run through physical obstructions that would otherwise stop a surface flood.
The sewage is pushed back, up and out of gulleys, manholes, pipes, toilets often straight into the heart of a house.
Sandbags don't stop it.
It is made worse these days by the modern systems used to pump sewage where in the past only gravity would have been used except in very difficult areas.
The entire sewer system in some areas is used as a holding tank for the pumps so the large pipes/sewers near the pumping stations are completely full of concentrated sewage at certain times during the pumping cycle.
I have seen sewage jetting up into the air from a road sewer access hole during a flood.
The jet, about 2 feet high, was being pushed through the eye used to open the cover.
I would describe the colour of the jet as coffee-coloured.
The majority is pushed back up through the sewage system by the flood waters.
The initial trapped-air voids within the sewers, compressed by flood water above spurting through manhole/access covers, pushes the entire sewer contents back up smaller pipes creating a thick "soup".
Often the sewage pipes are the first way some areas get flooded because they run through physical obstructions that would otherwise stop a surface flood.
The sewage is pushed back, up and out of gulleys, manholes, pipes, toilets often straight into the heart of a house.
Sandbags don't stop it.
It is made worse these days by the modern systems used to pump sewage where in the past only gravity would have been used except in very difficult areas.
The entire sewer system in some areas is used as a holding tank for the pumps so the large pipes/sewers near the pumping stations are completely full of concentrated sewage at certain times during the pumping cycle.
I have seen sewage jetting up into the air from a road sewer access hole during a flood.
The jet, about 2 feet high, was being pushed through the eye used to open the cover.
I would describe the colour of the jet as coffee-coloured.
